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Are “Ultraconserved” Genetic Elements Really Indispensable?

  • Liza Gross
  • Published: September 04, 2007
  • DOI: 10.1371/journal.pbio.0050253

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Less mutation or more correction?

Posted by plosbiology on 07 May 2009 at 22:20 GMT

Author: Stephen Elledge
Position: Professor
Institution: Harvard
E-mail: selledge@genetics.med.harvard.edu
Submitted Date: September 18, 2007
Published Date: September 20, 2007
This comment was originally posted as a “Reader Response” on the publication date indicated above. All Reader Responses are now available as comments.

A key issue regarding ultraconserved elements is the nature of their ultraconservation. There are at least two mechanisms that could account for that. One is that there is strong negative selection against changes. If the phenotypes have to do with subtle psychological defects for example, they may go unnoticed in laboratory conditions but have profound effects over evolutionary time. A second mechanism that could account for the high conservation might be a mechanism that enhances their correction to a reference sequence, i.e. the parental strand. If there were either a fool proof repair mechanism or a sequence fidelity correction mechanism that operates, perhaps in meiosis, to correct changes or eliminate cells that have differences, one might see reduced rates of evolution without functional selection. Of course, this does kick the question down the road a bit to ask why such a mechanism would exist. One idea might be that these sequences have roles in meiotic chromosome function such as recognition of homologs and could lead to subtle defects in fertility that only manifest themselves in a competitive mating environment over evolutionary time.

No competing interests declared.